The problem of marine fouling is of long standing. Any object which remains under water for an extended period of time becomes coated with various types and numbers of marine organisms, which settle in a general progression and sequence. On a clean surface there first collects a coating of a fine detritus which is followed by a bacterial coating and then a scummy algal growth, then by the attachment of larvae, and the growth of adult population which varies dependent on what larvae settle first. The large and abundant growth of algae can create a severe "soft" fouling condition, and the calcareous shells of acorn barnacles and serpulids are the primary cause of "hard" fouling.
The presence of fouling on a vessel's hull has well known detrimental effects. It reduces the top speed of the vessel, increases the power consumption and decreases the maximum range. It may also accelerate corrosion of hulls and structures. On sonar domes it reduces sonar performance by severely increasing "flow noise" thereby reducing substantially the signal-to-noise ratio.
Numerous preventive or anti-fouling methods have been proposed, the most successful of which is presently the use of toxic paint coatings. The practical life of such coatings is generally less than a few years, and the application and renewal of the paint requires drydocking of the vessel. Water jets, steam jets, abrasive cleaners and scrubbing are effective for removing fouling, but are very time consuming and cost prohibitive for frequent use. Cleaning while afloat is a desirable goal since anti-fouling paints and coatings cannot solve the problem alone.
A number of underwater brushing systems for cleaning ships while afloat are in use. These scrubbing systems are effective but time consuming, expensive, damage the paint, and are difficult to employ frequently and require diver control on most surfaces.